Practice Test 4 | Google Cloud Certified Professional Data Engineer | Dumps | Mock Test
You work as data engineer in an organization with large amount of data. This data is stored in Google BigTable for faster retrieval and update. Initially, the read and write latency was under threshold but with time the latency for both read and write operation is increased. What two steps you would take first in order to troubleshoot the issue?
A. Add more nodes to the cluster. The load across the node will be distributed instantly and will reduce the latency.
B. Use Key Visualizer feature for BigTable to zoom into specific key or time ranges to find details about hot spotting keys.
C. Look for row key pattern, like if the row key includes a timestamp by itself, all of the write will target a single node. Update the row key pattern to avoid hot spotting.
D. Export your Bigtable data into a new instance, and configure the new instance type with SSD’s.
The correct answer is B, C.
Option A is incorrect. Before adding nodes to the cluster, analyzing row key pattern is recommended approach. Also, after adding or removing nodes, it typically takes a few minutes under load for Cloud Bigtable to optimize the cluster’s performance. This option is also incorrect as distribution of load is not instantly.
Option B is correct. Refer – https://cloud.google.com/bigtable/docs/keyvis-overview
Key Visualizer is a tool that helps you analyze your Cloud Bigtable usage patterns. It generates visual reports for your tables that break down your usage based on the row keys that you access.
Key Visualizer can help you complete the following tasks:
- Check whether your reads or writes are creating hotspots on specific rows
- Find rows that contain too much data
- Look at whether your access patterns are balanced across all of the rows in a table
Option C is correct. To get the best performance out of Cloud Bigtable, it’s essential to think carefully about how you compose your row key. That’s because the most efficient Cloud Bigtable queries use the row key, a row key prefix, or a row range to retrieve the data. Using the timestamp by itself as the row key is not recommended, as most writes would be pushed onto a single node. For the same reason, avoid placing a timestamp at the start of the row key.
Option D is incorrect. As the question suggest choosing the steps first for troubleshooting the issue, making any decision to create a new instance is not correct. User need to first determine reason for hot spotting.
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